import math
import numpy as np

# J=0; dw1=0; dw2=0; db=0;
# for i = 1 to m
#     z(i) = wx(i)+b;
#     a(i) = sigmoid(z(i));
#     J += -[y(i)log(a(i))+(1-y(i)）log(1-a(i));
#     dz(i) = a(i)-y(i);
#     dw1 += x1(i)dz(i);
#     dw2 += x2(i)dz(i);
#     db += dz(i);
# J /= m;
# dw1 /= m;
# dw2 /= m;
# db /= m;